This invention is generally in the field of implantable miniaturized devices that provide controlled delivery or exposure of molecules or smaller devices. More specifically, the invention relates to implantable microchip devices.
U.S. Pat. No. 5,797,898 to Santini, et al. describes active or passive microchips for the delivery, i.e. release, of molecules such as drugs. These microchip devices contain reservoirs filled with the molecules to be released. In some embodiments, the reservoir openings must be sealed after they are filled to prevent leakage from or between any of the reservoirs.
One approach for sealing small reservoirs is to use a waterproof epoxy or other material impervious to any fluids surrounding the device. It is generally important, however, to avoid contacting the reservoir contents, particularly drug molecules, with chemical adhesives. The use of a chemical adhesive sealant may necessitate additional testing to determine the presence and nature of any interactions between the chemical adhesive and each drug or other chemical to be contained in and released from the reservoirs. The use of chemical adhesives also may require long times, high temperatures, and/or exposure to ultraviolet light in order to cure completely, processes that may degrade sensitive drug or chemical molecules in the reservoirs.
It is known that such adhesives and polymers generally cannot function as true hermetic seals over extended periods of time. Hermeticity, however, would be highly advantageous for microchip reservoirs to provide a controlled environment until the reservoirs are activated (i.e. opened). In fact, hermeticity likely is essential for most long term in vivo applications of such microchip devices. It would therefore be beneficial to provide methods of hermetically sealing a microchip device, including any control electronics and power source packaged with the device.
While hermetic sealing techniques are commonly found in implantable devices, such as pacemakers and cochlear implants, new or improved hermetic sealing methods are required for hermetically bonding a microchip reservoir device to an outer enclosure/packaging structure, which serves to protect the internal device components while also allowing a portion of the microchip reservoir device to contact/interface with the environment.
It would be desirable for seals incorporated within a microchip device for in vivo applications to prevent communication of drug, body fluids, or other substances between reservoirs or from the reservoirs into other portions of the microchip device. In addition, the seal desirably should withstand mechanical forces and chemical attack over time, and should not interfere with the process of opening reservoir caps and other aspects of the release processes. The materials forming the seals desirably are biocompatible, biostable, have very low or no permeability to water vapor and other materials, and should not react with the drug or other reservoir contents. Furthermore, the process of sealing should not degrade the reservoir contents, for example due to high temperatures, excessive vibratory forces, or exposure to incompatible chemicals or materials. It therefore would be advantageous to provide devices and methods for sealing the reservoirs of microchip devices for the controlled release of drugs and other molecules, which satisfy these several sealing parameters.